Braking device



Sept. 15, 1970 F K ETAL 3,528,530

v BRAKING DEVICE 4 Sheets-Sheet 1 Filed April 5, 1968 INVENTORS. HARRY C. FRANCK and HANS A. HJG

AGENT.

IFIG. 2(

Sept. 15, 1970 c, FRANCK .ETAL 3,528,530

BRAKING DEVICE Filed April 5. 1968 4 Sheets-Sheet :3

IN VENTORS. HARRY C. FRANCK and HANS A. HUG

AGENT.

Sept. 15, 1970 c. FRANCK ET AL 3,528,530

I BRAKING DEVICE 4 Sheets-Sheet 5 Filed April 5, 1968 I lN-VENTORS.

HARRY c. FRANCK and HANS A.HUG

GENT:

Spt. 15,1970 H. c. FRANCK ET AL BRAKING DEVICE 4 sheets-s et 4 Filed April ,5, 1968 s .R O T N E V N HARRY c. FRANCK land /vs A. HUG:

AG NT.

United States Patent Ofice 3,528,530 Patented Sept. 15, 1970 ABSTRACT OF THE DISCLOSURE A braking device adapted to be attached to a projectilelike package which is to be air-dropped or otherwise launched and operable to deploy upon striking the ground whereby the penetration into the earth of the package is limited. A braking device in accordance with a first embodiment of the invention comprises a plurality of inclined finger-like projections having weakened upper ends formed integrally with a collar employed to attach the braking device to a package, and a circumferential expansible pleated hoop encircling the lower ends of the projections. Upon striking the ground, the projections bend outwardly and the hoop is expanded to its maximum circumferential length, thereby increasing the effective diameter of the braking device and providing efiective braking action.

A braking device in accordance with an alternative embodiment of the invention for providing an increased amount of braking action is also disclosed.

BACKGROUND OF THE INVENTION The present invention relates to braking devices and, more particularly, to one-shot braking devices for controlling or limiting the penetration into the ground of airdropped or launched packages.

It is often desirable to air-drop or otherwise launch supplies or equiment from low altitudes to particular ground stations and cause them to permanently attach themselves to the ground as they strike the ground and remain substantially erect after impact. A typical situation, for example, where such a launching of packages is desirable, is the air-dropping from altitudes of a few hundred feet or so of automatic, unattended telemetry sensor stations. These sensor stations typically include devices for acquiring and telemetering data pertaining to temperature, wind velocity, seismic vibrations, etc., to a remote data-gathering station.

One method of air-dropping packages employed heretofore has been to securely locate equipment to be protected from damage in an end portion of a relatively long package having the general configuration of a projectile, and to air-drop the package to the ground. The projectile-like package penetrates the earth for substantially its entire length and, if the soil is reasonably hard, the equipment to be protected remains safely at a point substantially at ground level. It has been discovered, however, that if the soil penetrated by the package is soft or muddy, it is possible for the entire package to penetrate the earth and to completely disappear from sight. In this event, the equipment contained in the package is rendered useless, and any attempts to retrieve the buried equipment are greatly complicated, particularly if the exact point of penetration is lost or if the terrain is inaccessible. Therefore, unless some knowledge as to the strength of the soil in which packages are to be air-dropped has been available beforehand, as by performing tests on the soil, the success of the above-described method has been completely fortuitous and, therefore, impractical where repeated success is required.

As an alternative approach to that described herein:

above, parachutes of a variety of types have been used. However, because parachutes cannot accurately position packages at particular ground locations, and because of their susceptibility to interference by wind, trees, etc., they have not been entirely acceptable for the particular application described above. Moreover, where some penetration of equipment into the ground is desirable, as in the case of equipment for detecting earth tremors, parachutes are completely ineifective.

SUMMARY OF THE INVENTION Briefly, in accordance with the present invention, a oneshot braking device is provided which is adapted to be secured to a package which is to he air dropped or airor ground-launched. Upon striking the ground, the braking device is adapted to deploy in such a fashion that the penetration into the earth of the package is limited to a safe distance and the package is consequently prevented from being completely buried.

A braking device in accordance with a first embodiment of the invention comprises a body which includes a supporting portion and a plurality of elongated projections extending from the supporting portion, and an expansible member fixed to and linking the projections at a distance remote from the supporting portion. When the braking device strikes the ground after falling from a predetermined height, the individual projections deform at a substantially central region thereof as they gradually penetrate the earth, and the ends of the projections move gradually in a lateral direction such that the soil in the path of the deploying braking device is displaced and pushed aside, thereby providing e-tfective braking action. At the same time, the laterally-moving ends of the projections cause the expansible member to expand to a length exceeding its non-deployed length, the expanded expansible member then serving to substantially restrict further travel of the ends of the projections.

A one-shot braking device in accordance with an alternative embodiment of the invention utilizes the above-described braking device and, in addition, a cage-like section which is positioned above and fixed to the supporting portion of the above-described braking device. The cage-like section includes a second supporting portion similar to the first supporting portion and is spaced from and aligned with the first supporting portion. The cagelike section further includes a plurality of elongated outwardly-bowed members each fixed at one region to the first supporting portion and at the other end to the second supporting portion. The bowed members are positioned around the peripheries of the first and second supporting portions. When the braking device of the above construction deploys by striking the ground, the bottom portion of the braking device deforms in the manner previously described, the bowed members of the upper portion deform at substantially central regions thereof, and the first and second supporting portions abut each other and prevent further deformation of the bowed members.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of a braking device in accordance with a first embodiment of the invention prior to the braking device being deployed by striking the ground;

FIG. 2(a) is a cross-sectional view taken along a line 2-2 in FIG. 1 showing a circumferential expansible pleated hoop employed by the braking device of FIG. 1;

FIG. 2(b) is a plan view of an alternative embodiment of a circumferential expansible pleated hoop which may be used by the braking device of FIG. 1;

FIG. 3 illustrates a typical mounting arrangement for the braking device of FIG. 1 on a package which is to be air-dropped or otherwise launched;

FIG. 4 illustrates the position in the ground of the braking device and package after the braking device has fully deployed;

FIG. is a perspective view of the braking device of FIG. 1 after having fully deployed;

FIG. 6 is a perspective view of a braking device in accordance with an alternative embodiment of the invention prior to the braking device being deployed by striking the ground; and

FIG. 7 is a perspective view of the braking device of FIG. 6 after having fully deployed by striking the ground.

DESCRIPTION OF THE PREFERRED EMBODI- MENTS OF THE INVENTION BRAKING DEVICEFIGS. 1, 2(a), and 2(b) Referring to FIG. 1, there is shown a braking device 1 in accordance with a first embodiment of the invention. As shown in FIG. 1, the braking device 1 comprises two major sections, a main body or cage 2 and a circumferential expansible pleated hoop or strap 3 encircling the bottom part of the body 2. The body 2 further comprises a plurality of flat, rectangular, finger-like projections 4 preferably formed integrally with a cylindrical supporting portion or collar 6, each of the projections 4 being spaced from each other by a gap or slot 12 and inclined by a small angle with respect to the central axis of the braking device 1. A pair of tabs 5 separated by a slight distance at 5a are also formed integrally with the collar 6 to enable the braking device 1 to be tightly secured to a package when threaded bolts are inserted in a pair of openings 5b provided in each of the tabs 5.

Each of the projections 4 is preferably weakened at a region 7 by reducing the cross-sectional area at the upper end of each of the projections 4. The purpose of reducing the cross-sectional area is to enable the projections 4 to readily yield at the regions 7 and to deform quickly when an upward force F, for example, the force of the ground applying against the braking device upon impact, is applied to the lower extremities 4a of the projections 4. More particularly, when the upward force F is applied to the extremities 4a of the projections 4, the regions 7 act as hinges or flexure points causing the individual projections 4 to yield at the regions 7 and to buckle or collapse at the central regions thereof, the central regions being designated as 40 in FIG. 1. It is to be noted that the regions 7 further serve to reduce stress concentrations at the upper terminations of the gaps 12 and accordingly prevent tearing from occurring at such terminations. The slight inclination of each of the projections 4 also serves to aid the collapse of the projections 4. The above operation will become more fully apparent from a discussion of FIG. 5 to be presented hereinafter.

In the particular embodiment of FIG. 1, the weakening of the upper ends of the projections 4 is accomplished by means of a plurality of drilled holes 8 located intermediate the upper ends of adjacent ones of the projections 4. However, the same results may be achieved by notching the projections 4 at the regions 7, by scoring the surfaces of the projections 4 at the upper ends thereof, or by any other functionally equivalent means.

As briefly mentioned hereinabove, the second component section of the braking device 1 is the circumferential expansible pleated hoop or strap 3. As shown in FIG. 1, and more clearly in the cross-sectional view of FIG. 2(a), the circumferential hoop 3 consists of a thin, flat resilient band 3a having a plurality of pleats or bight portions 10 formed therein, the pleats 10 being interposed in the slots 12 between the lower extremities 4a of adjacent projections 4. The hoop 3 is secured to bottom regions of the projections 4 by means of rivets 14 inserted through holes 15 formed in the hoop 3. As will also become more fully apparent hereinafter from a discussion of FIG. 5, the main purpose of the hoop 3 is to restrict the amount of travel of the lower extremities 4a of the projections 4 as the upward force F is applied against the lower extremities 4a of the projections 4 causing the projections 4 to buckle or collapse at the central regions 4c. The hoop 3 also determines the manner in which the projections 4 are to collapse.

Although FIG. 1 illustrates the pleats 10 facing inward- 1y toward the center of the braking device 1, it is to be understood that the hoop 3 may be constructed such that the pleats face outwardly, as illustrated at 10 in FIG. 2(b). Furthermore, in lieu of the hoops shown in FIGS. 2(a) and 2(b), it is possible to use an expansible pleated hoop (the pleats facing inwardly or outwardly) formed from a high-strength wire cable and secured in any suitable manner to the lower regions of the projections 4. However, inasmuch as the hoop 3 of FIG. 2(a) provides the most satisfactory aerodynamic configuration when attached to the main body 2 of the braking device 1, and results in the most effective deployment of the braking device 1, the hoop 3 of FIG. 2(a) is the preferred form.

MOUNTING OF BRAKING DEVICEFIG. 3

FIG. 3 illustrates the manner in which the braking device 1 of FIG. 1 may be mounted on a package which is to be air-dropped or air-or ground-launched. For purposes of the present discussion, a projectile-type package 20 including a solid or hollow elongated cylindrical front portion 20a conforming to the cylindrical collar 6 of the braking device 1 will be considered. However, it is to be understood that the braking device 1 may be modified so as to conform to many other types of package configurations while retaining the above-described arrangement of the projections 4 and the hoop 3. In the package 20 shown in FIG. 3, the equipment which it is desired to locate safely at substantially ground level after the braking device 1 has fully deployed is enclosed in a section 20b of the package 20 (shown in dotted outline).

While the braking device 1 is shown in FIG. 3 as being mounted on the front portion 20a at a central region A thereof, the most desirable mounting location is determined from such factors as the weight of the package, the height from which the package is to fall, and the strength of the soil which is to be penetrated by the package (that is, the soil index). For example, for a package such as shown in FIG. 3 weighing approximately 40 pounds and having a front portion 20a of approximately 1 /2 ft., and dropped from a height of 500 ft., it has been found that with the central mounting of the braking device 1 (as shown in FIG. 3), the braking device 1 will effectively deploy in both hard and soft soils. More particularly, the braking device 1 will provide maximum retardation in soft soil while permitting a satisfactory degree of penetration in firm soil. Where some knowledge of the strength of the soil has been available beforehand, it has been found that a forward mounting location B is particularly effective for soft soils and a rearward mounting location C is particularly effective for hard soils.

As previously mentioned, the braking device 1 may be simply secured to the package 20 by means of threaded bolts inserted in the holes 5b provided in the tabs 5 (FIG. 1). This arrangement is generally satisfactory to secure the braking device 1 to a package. However, it has been found desirable in many applications to additionally coat the entire braking device 1 with a vinyl material (polyvinyl-chloride or PVC) which cold flows when the bolts are tightened thereby providing a non-slip bond between the braking device and the package. Another alternative is to provide a suitable retaining collar on the package such as shown in dotted outline at 20c in FIG. 3.

DEPLOYMENT OF BRAKING DEVICE FIGS. 4 and 5 When the package 20 such as shown in FIG. 3 is dropped from an airborne vehicle or launched from an airborne or ground station, the front portion 20a arrying the braking device 1 penetrates the ground initially, and then the braking device 1 makes contact with the ground and begins to deploy. The braking device 1 deploys in a gradual fashion, the projections 4 collapsing and dissipating kinetic energy gradually both by deforming and by displacing the soil until the package has come to a complete rest. The position in the ground of the package 20 and deployed braking device 1 after the package 20 has come to a complete rest is illustrated in FIG. 4. The final configuration of the deployed braking device 1 is illustrated more clearly in the perspective view of FIG. 5.

As is particularly apparent from FIG. 5 when the braking device 1 deploys, all of the projections 4 yield at the weakened regions 7 and assume the illustrated inverted substantially U-shaped or arched configurations, the total height of the braking device 1 being substantially reduced from its initial value. Moreover, the circumferential expansible pleated hoop 3 becomes unravelled or delooped, that is, the hoop 3 expands to its maximum circumferential length, such that the pleats originally present in the hoop 3 are completely opened by the outward lateral movements of the ends of the projections 4 as the crushing-deforming action takes place. At the same time, the lower extremities 4a of the projections 4 are confined within the circumference defined by the expanded hoop 3 and substantially restrained from erratic movement by virtue of being riveted to the hoop 3. Accordingly, the collapsed projections 4 are separated from each other by a substantially-equal distance.

It is to be further noted that the hoop 3 also allows the deployed diameter D of the braking device -1 (at the lower region of the braking device 1) to be substantially greater than the non-deployed diameter D of the braking device (FIGS. 1, 2(a), and 2(b)). The effect of this increased diameter is to increase the effective area available to provide the above-described braking action. In other words, if no circumferential expansible pleated hoop 3 were used, each of the projections 4 would collapse into substantially U-shaped configurations, the configurations being in the opposite direction to that shown in FIG. 5. That is, the U-shaped members would be upright. As a result, the deployed diameter would be less than D and the effective area available to provide braking actionwould be less. In fact, it is possible that the overall configuration of such a braking device could aid rather than hinder penetration into the earth.

BRAKING DEVICEALTERNATIVE EMBODIMENT-AUG. 6

FIG. 6 illustrates a braking device 30 in accordance with an alternative embodiment of the invention. The braking device 30 of FIG. 6 is particularly useful where a greater amount of braking action is required than in the case of the braking device 1 of FIG. 1 and where the total Weight of the braking device is not a significant factor. As shown in FIG. 6, the braking device 30 comprises a lower body or cage 2', a circumferential expansible pleated hoop or strap 3 encircling the bottom part of the lower body 2', and an upper body or section 35 joined to the lower body 2 at 36 as by a weld connection. The lower body 2' is the same as the body 2 shown in FIG. 1 with the exception that no tabs such as shown at 5 in FIG. 1 are employed in the braking device 30 of FIG. 6. Therefore, where appropriate, the same reference numerals in a primed form have been used in FIG. 6.

The upper body 35 comprises a plurality of circumferentially-positioned, rectangular, slightly-bowed, stavelike members 37 separated by a plurality of substantially equally-spaced slots or gaps 38. The bowed members 37 are weakened at upper, central, and lower regions thereof 37a, 37b, and 370, respectively, by means of a plurality of groups of drilled holes 40, 41, and 42, respectively, the central regions 37b of each of the members 37 being further made to more readily collapse by forming slight bends 37d therein. It is to be noted that the projections 4 of the lower body 2' are staggered or offset with respect to the group of bowed members of the upper body 35. The reason for this arrangement will become apparent from a discussion of FIG. 7.

The upper body 35 further includes a cylindrical supporting portion or collar 44 preferably welded to a region 39 of the upper body. The collar 44 is similar to the collar 6' and is adapted to mate with the collar 6 when the braking device 30 deploys. The mating of the collars 44 and 6 serves to limit the amount of the collapsing or deformation of the individual members 37. A plurality of threaded holes 46 are provided in the region 39 and the collar 44 through which bolts are inserted to secure the braking device 35 to a package.

BRAKING DEVICE, ALTERNATIVE EMBODI- MENTDEPLOYEDFIG. 7

FIG. 7 illustrates the final configuration of the braking device 35 of FIG. 6 after the braking device 35 has deployed by striking the ground. As is evident from FIG. 7, each of the projections 4' of the lower body 2 yields at the region 7' to conform to a substantially U-shape, the circumferential expansible hoop 3 expands to its maximum circumferential length, each of the bowed members 37 of the upper body 35 yield at the regions 37a, 37b, and 370 to conform to a substantially U- or V-shape, and the collars 6 and 44 make contact with each other. The lower body 2' of the braking device 35 collapses in the same manner as the body 2. of the braking device 1 of FIG. 1 but to a lesser extent. The reason for this lesser amount of collapse is that the upper body 35 also dissipates a great deal of the kinetic energy. That is, the upper body 35 dissipates a great deal of the kinetic energy that would otherwise have to be dissipated by the lower body 2' if no upper body were present. In any event, each of the deployed diameters D and D of the lower body 2' and the upper body 35, respectively, are considerably greater than the non-deployed diameters D and D FIG. 6, thereby affording a considerable amount of braking action.

It is to be further noted from FIG. 7 that the staggered relationship of the bowed members 37 and the projections 4 permits very effective braking action to take place inasmuch as braking action is provided at each point in a circumference defined by the diameter D In other words, as adjacent pairs of the projections 4 collapse, the bowed members 37 located above the gaps 12 separating the adjacent pairs also collapse, thereby spreading the braking action over a greater ground area than would be possible if the projections 4' and the bowed members 37 were not arranged in a staggered relationship.

EXPERIMENTAL BMKING DEVICE An experimental vinyl-coated braking device of the type shown in FIG. 1 was constructed and attached to an approximately 1 /2 ft. front portion of an approximately 3 ft. long package Weighing approximately 40 pounds, and air-dropped from a helicopter into medium strength soil from a height of 500 ft. The braking device was constructed to have the following specifications.

Materials: :main body portion of fiat aluminum stock; circumferential expansible pleated hoop of A sheet steel;

Weight: 1% lbs.

Height: approximately 7" Number and dimensions of projections: nine projections,

each approximately 4%" long and 1 wide Number of pleats: 9

Diameter of area-weakening hole-s: approximately /2" Collar diameter: approximately 3%," (inside) Non-deployed diameter (D approximately 4 (inside) The package and experimental earth braking device required approximately 6 seconds to reach the ground, developing an impact velocity of approximately ft./ sec. The package and braking device penetrated the ground to a total depth of slightly less than 3 ft. in approximately 3 milliseconds, the braking device assuming the general configuration shown in FIG. 5. The total height of the braking device decreased from approximately 7" to approximately 2%." and the diameter D increased from approximately 4% to approximately 9%" (D A second package similar to the first package but containing no braking device penetrated the same soil to a final depth of approximately ft., in other words, 2 feet more than the total length of the package.

It will now be apparent that novel braking devices have been disclosed in such full, clear, concise and exact terms so as to enable any person skilled in the art to which they pertain to make and use the same. It will also be apparent that various changes and modifications may be made in form and detail by those skilled in the art without departing from the spirit and scope of the invention.

What is claimed is:

1. A deployable braking device comprising:

a body including a supporting portion and a plurality of elongated projections having free extremities extending from the supporting portion; and

an expansible strap member fixed to and linking the projections at a distance remote from the supporting portion;

said expansible strap member expanding outwardly in a direction generally normal to the major surface thereof and to a length greater than its non-deployed length in response to deploying forces acting against the free extremities of the elongated projections, and further permitting the extremities of the projections to likewise move outwardly in the same direction as, and together with, the outwardly expanding strap member.

2. A deployable braking device comprising:

a hollow elongated member having a plurality of axial slots therein defining a plurality of elongated projections having free extremities; and

an expansible strap member fixed to and joining the projections at a distance remote from the termination of the axial slots in the elongated member;

said expansible strap member expanding outwardly in a direction generally normal to the major surface thereof and to a length greater than its non-deployed length in response to deploying forces acting against the free extremities of the elongated projections, and further permitting the extremities of the projections to likewise move outwardly in the same direction as, and together with, the outwardly expanding strap member.

3. A braking device comprising:

a body including a supporting portion and a plurality of elongated projections extending from the supporting portion; and

an expansible member fixed to and linking the projections at a distance remote from the supporting portion wherein the expansible member is a strap having a plurality of bight portions formed therein, each bight portion being positioned between adjacent points at which the expansible member is fixed to the projections.

4. A braking device in accordance with claim 3 wherein each bight portion extends inwardly between an adjacent pair of projections.

5. A braking device in accordance with claim 1 further including:

a cage-like section positioned above and fixed at a lower end region to said supporting portion;

said cage-like section including a second supporting portion similar to the first supporting portion and spaced from and aligned with the first supporting portion, and a plurality of elongated outwardlybowed members each fixed at one end region to the first supporting portion and at the other end region to the second supporting portion, said bowed members being positioned around the peripheries of the first and second supporting portions.

6. A braking device in accordance with claim 5 wherein each of said bowed members has a reduced crosssectional area at each end and at a substantially central region thereof.

7. A braking device in accordance with claim 6 wherein said plurality of bowed members are staggered relative to said plurality of elongated projections.

8. A braking device comprising:

a body including a supporting portion and a plurality of substantially equally-spaced elongated projections extending from the supporting portion;

each of said elongated projections having the end region near the supporting portion of a reduced cross-sectional area; and

an expansible member fixed to and linking the end regions of the projections remote from the supporting portion, said expansible member having a plurality of bight portions each of which is positioned between adjacent points at which the expansible member is fixed to the projections;

each of said projections being adapted in response to a force applied to a remote end thereof as the braking device deploys by penetrating into the earth after falling from a predetermined height to yield at the end region of reduced cross-sectional area and to deform at a substantially central region thereof, said expansible member being expanded by the laterally-moving remote ends of the collapsing projections to a length greater than its non-deployed length as limited by the number and expanded lengths of the individual bight portions, said expansible member when expanded thereafter operating to substantially restrict the further travel of the remote ends of the projections.

9. A braking device in accordance with claim 8 wherein each bight portion extends inwardly between an adjacent pair of projections.

10. A braking device in accordance with claim 8 wherein each of the elongated projections is inclined outwardly from the supporting portion by a small angle.

11. A braking device in accordance with claim 8 further including:

a cage-like section positioned above and fixed at a lower end region to said supporting portion;

said cage-like section including a second supporting portion similar to the first supporting portion and spaced from and aligned with the first supporting portion, and a plurality of substantially equallyspaced elongated outwardly-bowed members each fixed at one end region to the first supporting portion and at the other end region to the second supporting portion, said bowed members being positioned around the peripheries of the first and second supporting portions;

each of said bowed members being adapted in response to a force applied to the lower end region of the cage-like section as the cage-like section penetrates into the earth to yield at the end regions thereof and to deform at the substantia ly central region thereof, whereby said second supporting portion abuts said first supporting portion and prevents further deformation of the bowed members.

References Cited UNITED STATES PATENTS 3/1968 Wight et a1. 11/1968 De Gain.

U.S. Cl. X.R. 

